Purchase of accounting software

My company is purchasing SQL Accounting Software. Should I post this as office expense or intangible asset?

You should post them a letter to use QF, haha

It depends how much cost is, usage either own use or reselling etc?

Currently any asset (tangible or intangible) that costs less than £100 can be treated as an expense. With software, unless you are buying it outright (ie. it can never be taken away from you or turned off without your consent), it is a subscription. If the subscription period overlapped your year end, then part of it would be treated as a pre-payment.